1. Field of the Invention
This invention relates to an emergency mask, and more particularly to an emergency mask which detachably holds a canister containing air-purifying antidote, such as catalyzer and adsorbent, for removing noxious gas in the case of fire and other emergency.
2. Description of the Prior Art
Recently, emergency mask for use in case of fire and other emergency are required to remove not only white smoke and black smoke, but also noxious gases, such as carbon monoxide, hydrochloric acid, cyanic acid, chlorine, ammonia, benzene, aldehydes, nitrogen oxide, and the like. Various kinds of emergency masks have been proposed to cope with the noxious gas. For instance, emergency masks capable of detachably holding canisters loaded with antidote have been developed.
After having carried out various tests on the emergency masks proposed heretofore, the inventors have found out that the emergency masks of the prior art have a shortcoming in that the air-purifying ability of the antidote in the canister is rapidly deteriorated when the moist air expired from a person wearing the emergency mask (to be referred to as the "user's expiration", hereinafter) enters the canister.